Ultra low frequency ballistocardiograms (Bcg) and transcutaneous carotid artery pulse recordings (CP) will be made on patients of the Multiple Risk Factor Intervention Trial (MRFIT). Four clinical centers of MRFIT with 2700 patients are involved in this ancillary study. Bcg and CP are recorded on magnetic tape cassettes in standardized format controlled by a specialized data encoder. Cassettes are then mailed to the applicants' laboratory for analysis by digital computer. Analog recordings on the cassettes are converted to digital time series on industry compatible nine tract digital magnetic tape. This step is carried out on a Varian 620 computer system (minicomputer). Data from these "first pass" digital tapes are then edited to produce "second pass" archive tape with ideal properties for further processing. The editing procedure is accomplished on IBM 370 (maxicomputer). Digital time series of Bcg and CP are then analysed by a record reading program in maxicomputer. Standardized objective measurements of Bcg and CP obtained in this way will then be employed in crossectional analyses and multivariate prognostic calculations. Bcg and CP are expected to demonstrate response to interventions and add important independent contributions to known predictive power of established risk factors for coronary heart disease.